Mouse myeloma cells which have undergone mutations in immunoglobulin production will be isolated and characterized. Particular attention will be paid to cells which have defects in the glycosylation of the H chain. The structural defects in such H chains and the role of glycosylation in immunoglobulin metabolism will be studied. The nature of the defect in other mutants blocked in synthesis, assembly, and secretion will also be investigated. BIBLIOGRAPHIC REFERENCES: Immunoglobulin biosynthesis by the MOPC 173 mouse myeloma tumor and a variant spleen clone. Baumal, R. and Scharff, M.D. Journ. of Immun. 116:65-74, 1976. Mouse myeloma mutants blocked in assembly, glycosylation and secretion of immunoglobulin. J. Mol. Bio. 102:237-252, 1976. Weitzman, S. and Scharff, M.D.